单选题
As pointed out at the beginning of the passage, people used to think that air pollution_______.
A、
caused widespread damage in the countryside
B、
affected the entire eastern half of the United States
C、
had damaged effect on health
D、
existed merely in urban and industries areas.
【正确答案】
D
【答案解析】
[解析]由第一段第一句话可推知。
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